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Abstract:

An ink-jet printer including: an ink supply portion; a transport
mechanism; an ink-jet head; an inverting mechanism; and a controller is
provided. The controller is configured to control the ink-jet head to
perform an ordinary jetting operation and a marking jetting operation,
and is configured to control the ink-jet head and the inverting mechanism
such that only the ordinary jetting operation is performed on the one
surface of the printing medium without performing the marking jetting
operation, and the marking jetting operation is performed on the other
surface of the printing medium after inverting the printing medium with
the inverting mechanism.

Claims:

1. An ink-jet printer configured to perform printing on a sheet-shaped
printing medium, comprising: an ink supply portion through which an ink
stored in an ink tank is supplied; a transport mechanism configured to
transport the printing medium in a predetermined transport direction; an
ink-jet head which is arranged to face one surface of the printing medium
transported by the transport mechanism and in which a nozzle for jetting
ink droplets of the ink supplied from the ink tank toward the printing
medium is formed; an inverting mechanism configured to invert the
printing medium; and a controller configured to control the ink-jet head
to perform an ordinary jetting operation and a marking jetting operation,
the ordinary jetting operation being an operation in which the ink,
droplets are jetted toward an area of the printing medium, different from
an edge portion of the printing medium, and the marking jetting operation
being an operation in which the ink droplets are jetted toward a parts of
the edge portion of the printing medium, wherein the controller is
configured to control the ink-jet head and the inverting mechanism such
that only the ordinary jetting operation is performed on the one surface
of the printing medium without performing the marking jetting operation,
and the marking jetting operation is performed on the other surface of
the printing medium after inverting the printing medium with the
inverting mechanism.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority from Japanese Patent
Application No. 2008-078119, filed on Mar. 25, 2008, the disclosure of
which is incorporated herein by reference in its entirety. The present
application is a continuation application of U.S. patent application Ser.
No. 12/404,997 filed on Mar. 16, 2009.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an ink-let printer which performs
the printing by jetting ink liquid droplets onto a printing medium.

[0004] 2. Description of the Related Art

[0005] Conventionally, a technique is known in the field of the printing
apparatus, in which a marking is applied or affixed to a side end portion
of a printing medium on which, for example, images and letters are
printed. Such a marking is often formed, for example, in order that a
desired page can be easily found by a person who takes a book by the hand
when a large number of printing paper sheets are stacked and bound to
form the book such as a magazine or a dictionary. In relation to the
ink-jet printer for forming the marking at the side end portion of the
printing medium as described above, Japanese Patent Application.
Laid-open No. 2006-56068 (FIG. 1) describes an ink-jet printer, wherein
the borderless printing function is diverted so that the regular printing
(printing of, for example, desired images and/or letters) is performed on
a central portion of a printing medium, and ink liquid droplets are also
jetted onto an edge portion (fore edge) of the printing medium to form a
marking at a side end portion of the printing medium.

SUMMARY OF THE INVENTION

[0006] According to a knowledge of the present inventors, it is
appropriate that the ink, which forms the marking, is permeated in the
thickness direction of the printing medium, wherein it is easy for a user
to confirm the marking when the marking is viewed from the side of the
printing medium. However, in the case of the ordinary printing, it is
enough that the image or the text is printed, on only the surface of the
printing medium. Therefore, the ink jetting amount is regulated to such
an extent that the ink is not permeated into the back surface of the
printing medium in order to secure the quality of the printing medium
subjected to the printing or suppress the consumption of the ink.
Therefore, the ink is not sufficiently permeated in the thickness
direction of the printing medium when the ink liquid droplets are jetted
onto the surface of the printing medium in order to form the marking in
the same manner as in the ordinary printing, as performed by the ink-jet
printer described in the foregoing Japanese Patent Application Laid-open
No, 2006-56068. Therefore, in the case of the printing medium on which
the marking is formed by diverting the borderless printing function which
does not aim at the permeation of the ink in the thickness direction of
the printing medium, it is extremely difficult for the user to confirm
the marking formed by the ink-jet printer when the printing medium is
viewed from the side.

[0007] In view of the above, an object of the present invention is to
provide an ink-jet printer which forms a marking to be easily confirmed
from the side of the printing medium.

[0008] According to a first aspect of the present invention, there is
provided an ink-jet printer which performs printing on a sheet-shaped
printing medium, including:

[0009] an ink;

[0010] an ink tank which stores the ink;

[0011] a transport mechanism which transports the printing medium in a
predetermined transport direction;

[0012] an ink-jet head which faces one surface of the printing medium
transported by the transport mechanism and in which a nozzle for jetting
ink droplets of the ink supplied from the ink tank toward the printing
medium is formed; and

[0013] a controller which controls the ink-let head to perform an ordinary
jetting operation and a marking jetting operation, the ordinary jetting
operation being an operation in which the ink droplets are jetted toward
an area of the printing medium, different from an edge portion of the
printing medium, and the marking jetting operation being an operation in
which the ink droplets are jetted toward a part of the edge portion of
the printing medium in an amount greater than that used in the ordinary
jetting operation to form a marking at the edge portion.

[0014] According to the first aspect of the present invention, the ink,
which is landed on the printing medium in the marking jetting operation,
is permeated in a larger amount in the thickness direction of the
printing medium as compared with the ink which is landed on the printing
medium in the ordinary jetting operation. When the marking jetting
operation, which is different from the ordinary jetting operation, is
executed as described above, it is possible to form the marking which can
be easily confirmed from the side of the printing medium.

[0015] According to a second aspect of the present invention, there is
provided an ink-jet printer which performs printing on a sheet-shaped
printing medium, the ink-jet printer including:

[0016] inks which include a black pigment-ink and three color dye-inks of
magenta, cyan, and yellow;

[0017] a plurality of ink tanks which store the black pigment-ink and the
color dye-inks respectively;

[0018] a transport mechanism which transports the printing medium in a
predetermined transport direction;

[0019] an ink-jet head which faces one surface of the printing medium
transported by the transport mechanism and in which a black-ink nozzle
jetting the black pigment-ink toward the printing medium and color-ink
nozzles jetting the three color dye-inks respectively, toward the
printing medium; and

[0020] a controller which controls the ink-jet head such that the ink-jet
head performs an ordinary jetting operation in which ink droplets are
jetted toward an area, of the printing medium, different from an edge
portion of the printing medium; such that the ink-jet head performs a
marking jetting operation in which ink droplets are jetted toward a part
of the edge portion of the printing medium to form a marking; and such
that when a black marking is formed in the marking jetting operation, the
liquid droplets of the three color dye-inks are jetted from the color-ink
nozzles onto the printing medium to overlap with each other at the part
of the edge portion.

[0021] According to the second aspect of the present invention, when it is
required to form the black marking in the marking jetting operation, the
dye color inks, which are easily permeated into the printing medium as
compared with the pigment black ink, are used. Therefore, even when the
total consumption amount of the dye color inks is smaller than the
consumption amount of the ink required to form the black marking with
only the pigment black ink, the ink liquid droplets can be permeated in
the thickness direction of the printing medium.

[0022] The marking, which is easily conformable from the side of the
printing medium, can be formed by executing the marking jetting operation
which is different from the ordinary jetting operation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 shows a schematic arrangement of an ink-let printer
according to a first embodiment of the present invention.

[0029] FIGS. 7A and 7B show schematic plan views illustrating the printing
operation on the recording paper by the ink-jet printer according to the
first embodiment of the present invention, wherein FIG. 7A shows a
situation in which ink liquid droplets are jetted from nozzles, and FIG.
7B shows a situation in which the ink liquid droplets jetted from the
nozzles are landed on the recording paper.

[0030]FIG. 8 shows a schematic plan view illustrating the printing
operation on the recording paper by a conventional ink-jet printer.

[0031] FIG. 9 shows a top view illustrating an ink-jet head according to a
second embodiment of the present invention.

[0032] FIG. 10A to 10D show schematic sectional views illustrating the
printing operation on the recording paper by the ink-jet printer
according to the second embodiment of the present invention, wherein FIG.
10A shows a situation in which a solvent is jetted from solvent-jetting
nozzles, FIG. 10B shows a situation in which the solvent jetted from the
solvent-jetting nozzles is landed on the recording paper, FIG. 10C shows
a situation in which ink liquid droplets are jetted from nozzles, and
FIG. 10D shows a situation in which the ink liquid droplets jetted from
the nozzles are landed on the recording paper.

[0033]FIG. 11 shows a top view illustrating an ink-jet head according to
a third embodiment of the present invention.

[0034]FIG. 12 shows a schematic arrangement of an ink-jet printer
according to a fourth embodiment of the present invention.

[0035]FIG. 13 shows a schematic sectional view illustrating an ink-jet
printer according to a fifth embodiment of the present invention.

[0036] FIGS. 14A to 14D illustrate transport states of the recording paper
in the ink-jet printer according to the fifth embodiment of the present
invention, wherein FIG. 14A shows a situation in which the recording
paper is fed, FIG. 14B shows a situation in which the printing operation
is performed on one surface of the fed recording paper, FIG. 14C shows a
situation in which the recording paper having been subjected to the
printing operation on one surface is inverted, and FIG. 14D shows a
situation in which the printing operation is performed on the other
surface of the inverted recording paper.

[0037]FIG. 15 shows a schematic plan view illustrating the printing
operation on the recording paper by the ink-jet printer according to the
fifth embodiment of the present invention.

[0038]FIG. 16 shows a schematic sectional view illustrating an ink-jet
printer according to a sixth embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

[0039] A first embodiment of the present invention will be explained
below. An ink-jet printer according to the first embodiment prints, for
example, desired letters and/or images on the recording paper by jetting
liquid droplets of inks of four colors (cyan, magenta, yellow, and black)
onto the sheet-shaped recording paper (printing medium) from nozzles
provided for an ink-jet head. The sheet-shaped printing paper includes,
for example, thin paper sheets, thick paper sheets, and films.

[0040] At first, the ink-jet printer will be explained. FIG. 1 shows a
schematic arrangement of the ink-jet printer according to the first
embodiment of the present invention. As shown in FIG. 1, the ink-jet
printer 1 includes a carriage 2 which is movable in the left-right
direction (scanning direction) as shown in FIG. 1, the ink-jet head 3 of
the serial type in which the nozzles 40 are formed. (see FIGS. 2 to 4)
and which is provided on the carriage 2 to jet the ink liquid droplets
with respect to the recording paper P, transport rollers 5 (transport
mechanism) which transport the recording Paper P in the frontward
direction (paper feeding direction: transport direction) as shown in FIG.
1, and a control unit (controller) 6 (see FIG. 5) which controls
respective constitutive components of the ink-jet printer 1.

[0041] The carriage 2 is provided so that the carriage 2 is
reciprocatively movable in the scanning direction along a guide shaft 8
which is arranged to range over two side wails of a frame (main body
frame) 4. The carriage 2 is movable in the scanning direction to the area
disposed outside the printing paper P (area deviated from the recording
paper P as viewed in the ink jetting direction). The ink-jet head 3 is
carried on the carriage 2. The ink-jet head 3 jets the ink liquid
droplets onto the recording paper P transported by the transport rollers
5, from the nozzles 40 provided on the lower surface of the ink-jet head
3, while making the reciprocating movement in the scanning direction
together with the carriage 2.

[0042] The transport rollers 5 are fixed to a rotary shaft 7 which is
arranged to range over the two side walls of the frame 4. When the rotary
shaft 7 is rotated about the center of the axis, then the transport
rollers 5 are rotated together with the rotary shaft 7, and the recording
paper P is transported in the paper feeding direction.

[0043] Next, the ink-jet head 3 will be explained in detail. FIG. 2 shows
a top view illustrating the ink-jet head. FIG. 3 shows a partial
magnified view illustrating those shown in FIG. 2. FIG. 4 shows a
sectional view taken along a. IV-IV line shown in FIG. 3. However, in
order to understand the drawings more comprehensively, pressure chambers
34 and through-holes 35, 36, 39, which are depicted in FIG. 3, are
omitted from the illustration in FIG. 2, and the nozzles 40 are depicted
to be large as compared with FIGS. 3 and 4.

[0044] As shown in FIGS. 2 to 4, the ink-jet head 3 has a flow passage
unit 22 which is formed with ink flow passages including the nozzles 40
and the pressure chambers 34, and a piezoelectric actuator 23 which jets
the ink, liquid droplets from the nozzles 40 of the flow passage unit 22
by applying the pressure to the inks contained in the pressure chambers
34.

[0045] At first, the flow passage unit 22 will be explained. The flow
passage unit 22 has a cavity plate 30, a base plate 31, and a manifold
Plate 32 each of which is formed of a metal material such as stainless
steel, and a nozzle plate 33 which is formed of an isolative material
(for example, a high molecular weight synthetic resin material such as
polyamide). The four plates 30 to 33 are joined to one another in a
stacked state.

[0046] The nozzle plate 33 is formed with the plurality of nozzles 40 as
through-holes. The plurality of nozzles 40 are arranged in the paper
feeding direction (in the upward-downward direction as shown in FIG. 2)
to form nozzle arrays 41. The four nozzle arrays 41 as described above
are arranged, side by side, in the scanning direction. The inks of four
colors of black, yellow, cyan, and magenta are jetted from the nozzles 40
belonging to the four nozzle arrays 41 respectively.

[0047] In this embodiment, a pigment ink is used for the black ink, and
dye inks are used for the other three color inks of yellow, cyan, and
magenta. In the pigment ink, the pigment component is dispersed in a
particle form in a solvent without being dissolved in surfactant or water
as a solvent. When the pigment ink is jetted from the nozzles 40 onto the
recording paper P, then the particles of the pigment component remain on
the surface of the recording paper P, and the particles themselves form
the color. In the dye ink, the dye component is dissolved in surfactant
or water as a solvent. When the dye ink is jetted from the nozzles 40
onto the recording paper P, then the solvent, in which the dye component
is dissolved, is permeated into the recording paper P, and thus the color
is formed. In general, the dye ink is easily permeated in the thickness
direction of the recording paper P as compared with the pigment ink.

[0048] As shown in FIGS. 3 and 4, the cavity plate 30 is formed with the
plurality of pressure chambers 34 corresponding to the plurality of
nozzles 40. Each of the pressure chambers 34 has a substantially elliptic
shape in which the scanning direction is the longitudinal direction
thereof. The pressure chambers 34 are arranged so that the right ends of
the pressure chambers 34 are overlapped with the nozzles 40 as viewed in
a plan view. Through-holes 35, 36 are formed at positions of the base
plate 31 overlapped with the both ends of the pressure chambers 34 in the
longitudinal direction as viewed in a plan view respectively.

[0049] Four manifold flow passages 37, which correspond to the four nozzle
arrays 41 respectively, are formed for the manifold plate 32. As shown in
FIGS. 2 to 4, each of the manifold flow passages 37 extends in the paper
feeding direction at the left position of the corresponding nozzle array
41. Further, the manifold flow passage 37 is overlapped with
substantially left halves of the corresponding pressure chambers 34 as
viewed in a plan view. As shown in FIG. 2, ends of the four manifold flow
passages 37 (ends on the upstream side in the paper feeding direction:
upper ends as shown in FIG. 2) are communicated with four ink supply
ports 38 which are formed for the cavity plate 30 disposed at the
uppermost layer respectively. The four ink supply ports 38 are connected
to four unillustrated ink tanks respectively. The inks contained in the
ink tanks are supplied from the ink supply ports 38 to the manifold flow
passages 37. Through-holes 39 are formed at positions of the manifold
plate 32 overlapped, with both of the through-holes 36 of the base plate
31 and the nozzles 40 of the nozzle plate 33 as viewed in a plan view.

[0050] As shown in FIG. 4, the manifold flow passages 37, which are
connected to the ink supply ports 38, are communicated with the pressure
chambers 34 via the through-holes 35 in the flow passage unit 22. The
pressure chambers 34 are further communicated with the nozzles 40 via the
through-holes 36, 39. In other words, the flow passage unit 22 is formed
with a plurality of individual ink flow passages which range from the
outlets of the manifold flow passages 37 to arrive at the nozzles 40 via
the pressure chambers 34.

[0051] Next, the piezoelectric actuator 23 will be explained. The
piezoelectric actuator 23 has a vibration plate 50, a piezoelectric layer
51, and a plurality of individual electrodes 52. The vibration plate 50
is composed of a conductive material such as a metal material. The
vibration plate 50 is joined to the upper surface of the cavity plate 30
so that the plurality of pressure chambers 34 are covered therewith. The
conductive vibration plate 50 also serves as a common electrode to allow
the electric field to act on the portions of the piezoelectric layer 51
interposed between the vibration plate 50 and the plurality of individual
electrodes 52 as described later on. The vibration plate 50 is connected
to the ground wiring of a head driver 54 (see FIG. 5), and the vibration
plate 50 is always retained at the ground electric potential.

[0052] The piezoelectric layer 51 is composed of a piezoelectric material
containing a main component of lead titanate zirconate (PZT) having the
ferroelectric property as a mixed crystal of lead titanate and lead
zirconate. The piezoelectric layer 51 is arranged continuously to range
over the plurality of pressure chambers 34 on the upper surface of the
vibration plate 50. The piezoelectric layer 51 is previously polarized in
the thickness direction thereof.

[0053] The plurality of individual electrodes 52 are provided
corresponding to the plurality of pressure chambers 34 on the upper
surface of the piezoelectric layer 51. The individual electrode 52 has a
substantially elliptic shape which is one size smaller than the pressure
chamber 34. The individual electrodes 52 are arranged at positions
overlapped with substantially central portions of the pressure chambers
34 as viewed in a plan view. One end of each of the individual electrodes
52 in the longitudinal direction (left end as shown in FIG. 3) extends
leftwardly to a position not overlapped with the pressure chamber 24 as
viewed in a plan view. The forward end thereof is a contact 52a. The head
driver 54 is connected to the contact 52a via a wiring member such as an
unillustrated flexible printed circuit (FPC). Any one of electric
potentials of a predetermined driving electric potential and the ground
electric potential is selectively applied from the head driver 54 to the
plurality of individual electrodes 52.

[0054] An explanation will be made about the function of the piezoelectric
actuator 23 having the feature as described above. When the pressure is
not applied to the ink. (when the ink liquid droplets are not jetted from
the nozzles 40), the electric potentials of the plurality of individual
electrodes 52 are previously retained at the ground electric potential by
the head driver 54. Starting from this state, when the predetermined
driving electric potential is applied to any one of the plurality of
individual electrodes 52 by the head driver 54, then the electric
potential difference is generated between the individual electrode 52 to
which the driving electric potential is applied and the vibration plate
50 as the common electrode which is retained at the ground electric
potential, and the electric field is generated in the thickness direction
at the portion of the piezoelectric layer 51 interposed between the
individual electrode 52 and the vibration plate 50. In this situation,
when the direction of polarization of the piezoelectric layer 51 is the
same as the direction of the electric field, then the piezoelectric layer
51 is elongated in the thickness direction, and the piezoelectric layer
51 is shrunk in the in-plane direction. The portion of the vibration
plate 50, which is opposed to the pressure chamber 34, is deformed so
that the portion protrudes toward the pressure chamber 34 (unimorph
deformation) in accordance with the shrinkage deformation of the
piezoelectric layer 51. In this situation, the volume of the pressure
chamber 34 is decreased. Therefore, the pressure of the ink contained
therein is raised, and the ink liquid droplets are jetted from the nozzle
40 communicated with the pressure chamber 34.

[0055] In the arrangement as described above, the ink-jet printer 1
performs the following two operations while reciprocatively moving she
ink-jet head 3 in the scanning direction together with the carriage 2. At
first, in the ordinary jetting operation, the ink-jet head 3 jets the ink
liquid droplets onto an area Pb (hereinafter referred to as "printing
area Pb") except for an edge portion Pa on the surface of the recording
paper P. Further, in the marking jetting operation, the ink-jet head 3
jets the ink liquid, droplets onto the edge portion Pa of the recording
paper P. Accordingly, for example, images and/or letters are printed on
the printing area Pb of the recording paper P, and the marking is formed
at a side end portion Pc as the end surface of the recording paper P (see
FIG. 6).

[0056] Next, an explanation will be made about the control unit 6 which
manages the overall control of the ink-jet printer 1. FIG. 5 shows a
block diagram illustrating the electric arrangement of the ink-jet
printer. FIG. 6 shows a perspective view illustrating a Plurality of
stacked printing paper sheets.

[0057] As shown in FIG. 5, the control unit 6 (control mechanism)
comprises, for example, Central Processing Unit (CPU) which serves as the
central processing unit, Read Only Memory (ROM) which stores, for
example, various programs and data for controlling the overall operation
of the ink-jet printer 1, and Random Access Memory (RAM) which
temporarily stores, for example, data to be processed by CPU.

[0058] Further, the control unit 6 functions as a recording control
section 71, a marking control section 72, a transport control section 73,
and a carriage control section 74. The recording control section 71
controls the head driver 54 of the ink-jet head 3 on the basis of the
data inputted from an input device 50 such as PC to perform the ordinary
jetting operation such that the ink liquid droplets are jetted from the
nozzles 40 onto the printing area Ph of the recording paper P. The
marking control section 72 controls the head driver 54 of the ink-jet
head 3 on the basis of the data inputted from the input device 50 such as
PC to perform the marking jetting operation such that the ink liquid
droplets are jetted from the nozzles 40 onto the edge portion Pa of the
recording paper P.

[0059] The transport control section 73 controls the transport motor 53
for driving and rotating the transport rollers 5 by the aid of the rotary
shaft 7 so that the transport rollers 5 are rotated, and thus the
recording paper P is transported in the paper feeding direction. The
carriage control section 74 controls the carriage-driving motor 51 so
that the carriage 2 is reciprocatively driven in the scanning direction.

[0060] An explanation will, now be made about the printing operation
performed by the ink-let printer 1. FIGS. 7A, 7B show schematic
cross-sectional views illustrating the printing operation on the
recording paper by the ink-jet printer according to the first embodiment
of the present invention, wherein FIG. 7A shows a situation in which the
ink droplets are jetted from the nozzles, and FIG. 7B shows a situation
in which the ink droplets jetted from the nozzles are landed on the
recording paper. FIG. 8 shows a schematic cross-sectional view
illustrating the printing operation on the recording paper by a
conventional ink-jet printer.

[0061] At first, the printing data is fed from the input device 50 to the
control unit 6 of the ink-jet printer 1. Accordingly, in the ink-jet
printer 1, the transport control section 73 controls the transport motor
53 on the basis of the printing data to rotate the transport rollers 5.
Accordingly, the recording paper P is intermittently transported by every
one line in the paper feeding direction, while the carriage-driving motor
51 is controlled by the carriage control section 74 to reciprocatively
drive the carriage 2 in the scanning direction. Simultaneously therewith,
the recording control section 71 controls the head driver 54 to perform
the printing in an amount corresponding to one line from the nozzles 40
as the ordinary jetting operation.

[0062] The printing data, which is inputted from the input device 50,
includes the position data of the side end portion Pc of the recording
paper P for forming the marking. The position data of the side end
portion Pc includes, for example, the information regarding the position
of the side end portion Pc in the paper feeding direction, and the
information about which end, of the recording paper P in the paper
feeding direction, the side end portion Pc is provided at. When the
marking Pd is formed at any side end portion Pc, of the both side end
portions Pc, overlapped in the scanning direction with the line on the
recording paper P on which the ordinary jetting operation is performed,
the head driver 54 is controlled by the marking control section 72 to let
the ink droplets from the nozzles 40 capable of jetting the desired color
as the marking jetting operation for the nearest edge portion Pa
overlapped in the scanning direction with the side end portion Pc of the
recording Paper P.

[0063] As shown in FIG. 7A, in the marking jetting operation, when the
ink-jet head 3 is moved toward the recording paper P from the outside
thereof in the scanning direction (from the right to the left in FIG.
7A), i.e., when the nozzle 40, which is capable of jetting the desired
color, is moved toward the recording paper P from the outside thereof,
then the control unit 6 controls the head driver 54 to jet the ink
droplets from the nozzle 40 toward the edge portion Pa of the recording
paper P. In other words, after the ink-jet head 3 mounted on the carriage
2 is moved rightward in FIG. 7A to the outside of the recording paper P,
the ink-jet head 3 is turned and moved leftward. Then the control unit 6
controls the head driver 54 to jet the ink droplets from the nozzle 40.
Accordingly, the ink droplets, which are jetted from the nozzle 40, have
the velocity component in the direction to approach the recording paper
P. Therefore, the ink droplets are allowed to fall while being inclined
in the direction to approach the recording Paper P with respect to the
vertical direction (upward-downward direction in FIG. 7), and the ink
droplets are landed on the side end portion Pc and/or the edge portion Pa
of the recording paper P. In other words, the range, in which the ink
droplets jetted from the nozzle 40 to form the marking can be landed, is
widened, and the landing accuracy is improved.

[0064] The jetting of the ink in the printing area and the jetting of the
ink to form the marking Pd at the edge Portion may be performed in one
time of she scanning operation (in a same one-way scanning), or they may
be performed in the distinct scanning operations. In other words, a
separate scanning, which is to be performed in order to form the marking
Pd at the edge portion, may be performed independently from the ordinary
scanning. For example, when the two-way printing is performed to let the
inks while reciprocatively moving the ink-jet head 3 in the left-right
direction in FIG. 7, then the formation of the marking Pd and the
printing on the printing area Pb may be performed in the scanning in one
route (scanning directed from the right to the left), and only the
printing on the printing area Ph may be performed in the scanning in the
return route (scanning directed from the left to the right). In this
procedure, after completing the scanning in the return route, the ink-jet
head 3 may be further subjected to a short scanning from the right to the
left in order to form the marking Pd before proceeding to the next
scanning in the one route. In this case, it is not necessarily
indispensable that the ink-jet head 3 is subjected to the scanning to
cover the entire recording paper P in the widthwise direction thereof. It
is enough that the ink-jet head 3 is subjected to the scanning to cover
only the edge portion Pa of the recording paper P at which the marking Pd
is formed.

[0065] A larger amount of the ink is permeated into the area of the
recording paper P in which the marking Pd is formed as compared with the
area in which the inks are jetted in the printing area as described later
on. Therefore, the period of time, which is required to dry the ink in
the area formed with the marking Pd, is longer than the period of time
which is required to dry the inks in the printing area. Accordingly, when
the marking Pd is formed on the recording paper P in the certain
scanning, a period of time may be allowed to elapse to some extent before
moving the recording paper P in the transport direction in order to
proceed to the next scanning. In this case, the process may wait for a
certain period of time in a state in which the ink-jet head 3 is stand
still, or the process may wait for a certain period of time in a state in
which the ink-jet head 3 is subjected to the scanning. When the ink-jet
head 3 is subjected to the scanning, then the inks may be jetted only in
the printing area, or the empty scanning may be performed without jetting
the inks. In any case, when the ink-jet head 3 is subjected to the
scanning, the flow of the air arises. Therefore, the ink, which is in the
area formed with the marking Pd, can be quickly dried.

[0066] As shown in FIG. 8, when the jetting amount of the ink droplets per
unit area or areal size, i.e., per one dot subjected to the jetting from
the nozzle 40 onto the recording paper P (ink landing amount per one dot
of the recording paper P) is equivalent, between the ordinary letting
operation and the marking letting operation, then the degree of
permeation in the thickness direction of the ink for forming the marking
Pd into the recording paper P is low, and it is extremely difficult to
visually confirm the marking Pd, when the marking Pd, which is formed
with the concerning ink landing amount, is visually confirmed from the
side of the recording paper P (in the left direction in FIG. 8).

[0067] Accordingly, in this embodiment, the control unit 6 controls the
head driver 54 of the ink-jet head 3 so chat the jetting amount (landing
amount) of the ink droplets per unit area onto the recording paper P in
the marking jetting operation is larger than the jetting amount. (landing
amount) of the ink liquid droplets per unit area onto the recording paper
P in the ordinary jetting operation.

[0068] Specifically, the control unit 6 controls the head driver 54 so
that the liquid droplets, which have larger volumes, are jetted from the
nozzle 40 in the marking jetting operation as compared with the ordinary
jetting operation. Accordingly, as shown in FIG. 7B, the ink droplets can
be more permeated in the thickness direction of the recording paper P in
the marking letting operation as compared with the ordinary jetting
operation. In other words, it is possible to form the marking Pd which
can be easily confirmed from the side of the recording paper P.

[0069] In order that the jetting amount of the ink droplets per unit area
onto the recording paper P in the marking jetting operation is larger
than the jetting amount of the ink liquid droplets per unit area onto the
recording paper P in the ordinary jetting operation, the following
technique is also available, without being limited to only the technique
in which the control unit 6 controls the head driver 54 to jet the liquid
droplets having the larger liquid droplet volumes from the nozzle 40 in
the marking jetting operation as compared with the ordinary jetting
operation.

[0070] For example, the control unit 6 may control the ink-jet head 3 so
than the number of times of jetting of the ink droplets per unit area
onto the recording paper P in the marking jetting operation is larger
than the number of times of jetting of the ink droplets per unit area
onto the recording paper P in the ordinary jetting operation.
Accordingly, the ink droplets can be more permeated in the thickness
direction of the recording paper P by jetting the ink droplets having the
sizes used in the ordinary jetting operation from the nozzle 40, without
jetting the large ink droplets not used in the ordinary jetting operation
from the nozzle 40 in order to perform the marking jetting operation.

[0071] When it is required to form the black marking Pd at the edge
portion Pa of the recording paper P in the marking jetting operation, the
control unit 6 controls the head driver 54 so that the three color inks
in the same amount are jetted in an overlapped or superimposed manner
onto the recording paper P from the nozzles 40 for jetting the inks of
yellow, cyan, and magenta as the dye inks respectively. Accordingly, the
black (so-called tri-color black) marking Pd is appropriately formed as
well. As described above, when it is required to form the black marking
Pd, the tri-color black is used with the dye color inks which are easily
permeated into the recording paper P as compared with the pigment black
ink. Therefore, even when the total consumption amount of the dye color
inks is smaller than the ink consumption amount required to form the
black marking Pd with only the pigment black ink, the ink liquid droplets
can be Permeated into the thickness direction of the recording paper P.
In another case, even when the printing is performed with the dye black
ink on the printing area Pb of the recording paper P, the black
(so-called tri-color black) marking Pd may be formed by jetting the same
amount of the inks of yellow, cyan, and magenta as the dye inks
respectively in an overlapped manner onto the edge portion Pa. In this
procedure, the control can be made such that the ink amount per one dot
is larger when the three type of the dye inks are jetted onto the edge
portion Pa as compared with when the dye black ink is jetted onto the
printing area Pb. When the control is performed as described above, the
ink amount permeated in the thickness direction of the recording paper at
the edge portion Pa is larger than the ink amount permeated in the
thickness direction of the recording paper at the printing area Pb.
Accordingly, it is possible to form the marking Pd which can be easily
confirmed from the side of the recording paper P.

[0072] As described above, in the case of the ink-jet printer 1 of the
embodiment of the present invention, the ink droplets, which are jetted
onto the recording paper P in the marking jetting operation, are more
permeated in the thickness direction of the recording paper P as compared
with the ink liquid droplets which are jetted onto the recording paper P
in the ordinary jetting operation. In this way, when the marking jetting
operation, which is different from the ordinary jetting operation, is
executed, it is possible to form the marking Pd which can be easily
confirmed from the side of the recording paper P. The moving mechanism of
the present invention corresponds to the structure in which the carriage
control section 74 controls the carriage-driving motor 51 to move the
carriage 2 mounting the ink-jet head 3.

Second Embodiment

[0073] Next, a second embodiment of the present invention will be
explained. FIG. 9 shows a top view illustrating an ink-jet head according
to the second embodiment of the present invention. FIG. 10A to 10D show
schematic plan views illustrating the printing operation on the recording
paper by the ink-jet printer according to the second embodiment of the
present invention, wherein FIG. 10A shows a situation in which a solvent
is jetted from solvent-jetting nozzles, FIG. 10N shows a situation in
which the solvent jetted from the solvent-jetting nozzles is landed on
the recording paper, FIG. 10C shows a situation in which ink droplets are
jetted from nozzles, and FIG. 10D shows a situation in which the ink
droplets jetted from the nozzles are landed on the recording paper.

[0074] In the ink-jet printer of this embodiment, the ink-let head 3 of
the first embodiment is merely additionally provided with the plurality
of solvent-jetting nozzles which jet the solvent to enhance the degree of
permeation of the ink into the recording paper P. The other components or
parts are constructed in the same manner as in the first embodiment. The
components or parts, which are the same as or equivalent to those of the
first embodiment, are designated by the same reference numerals, any
explanation of which will be omitted.

[0075] As shown in FIG. 9, the ink-jet head 203 has the plurality of
solvent-jetting nozzles 240 which are aligned in the paper feeding
direction (in the upward-downward direction as shown in FIG. 9) on the
right side in FIG. 9 and which form a nozzle array 241, in addition to
the plurality of nozzles 40 which constitute the four nozzle arrays 41.
The nozzle array 241 is arranged, side by side, in the scanning direction
together with the four nozzle arrays 41. The solvent, which is jetted
from the solvent-jetting nozzles 240, includes, for example, glycol
ethers represented by alkyl ethers such as ethylene glycol system and
propylene glycol system.

[0076] An explanation will now be made about the marking jetting operation
performed by the ink-jet printer according to this embodiment. At first,
as shown in FIG. 10A, the control unit 6 controls the head driver 54 so
that the solvent is jetted from the solvent-jetting nozzles 240 toward
the edge portion Pa of the recording paper P. Accordingly, as shown in
FIG. 10B, the solvent, which is landed on the edge portion Pa of the
recording paper P, is permeated in the thickness direction of the edge
portion Pa of the recording paper P.

[0077] After that, as shown in FIG. 10C, the control unit 6 controls the
head driver 54 so that the ink droplets are jetted from the nozzle 40
onto the landing position which is the same position as that of the edge
portion Pa of the recording paper P on which the solvent has been landed.
Accordingly, as shown in FIG. 10D, the ink droplets, which are jetted
from the nozzle 40, are landed on the same position, of the edge portion
Pa of the recording paper P, onto which the solvent has been jetted. The
ink droplets are permeated in the thickness direction of the recording
paper P in accordance with the action of the solvent no form the marking
Pd, as compared with a case in which the ink droplets are landed on the
recording paper P into which the solvent is not permeated. In this
embodiment, the marking jetting operation is the series of operations in
which the control unit 6 controls the head driver 54 to jet the solvent
from the solvent-jetting nozzles 240 onto the edge portion Pa of the
recording paper P, and then the ink droplets are jetted from the nozzles
40 onto the same position, of the edge portion Pa of the recording paper
P, onto which the solvent has been jetted from the solvent-jetting
nozzles 240.

[0078] Accordingly, the ink droplets, which are jetted onto the recording
paper P in the marking jetting operation, can be more permeated in the
thickness direction of the recording paper P, as compared with the ink
droplets which are jetted onto the recording paper P in the ordinary
jetting operation. Therefore, it is possible to form the marking Pd which
can be easily confirmed from the side of the recording paper P.

Third Embodiment

[0079] Next, a third embodiment of the present invention will be
explained. FIG. 11 shows a top view illustrating an ink-jet head
according to the third embodiment of the present invention. In an ink-jet
printer of this embodiment, the ink-jet head 3 of the first embodiment is
merely additionally provided with marking ink-jetting nozzles for jetting
a marking ink. The other components or parts are constructed in the same
manner as in the first embodiment. The components or parts, which are the
same as or equivalent to those of the first embodiment, are designated by
the same reference numerals, any explanation of which will be omitted.

[0080] As shown in FIG. 11, the ink-jet head 303 has the plurality of
marking ink-jetting nozzles 340 which are aligned in the paper feeding
direction (in the upward-downward direction as shown in FIG. 11) on the
right side in FIG. 11 and which form a nozzle array 341, as well as the
plurality of nozzles 40 which constitute the four nozzle arrays 41. The
nozzle array 341 is arranged, side by side, in the scanning direction
together with the four nozzle arrays 41. The marking ink, which is jetted
from the marking ink-jetting nozzles 340, is an ink to be exclusively
used for the marking as prepared by mixing the ink to be used for the
ordinary jetting operation such as the ink jetted from the nozzles 40 and
a solvent to enhance the degree of permeation of the ink into the
recording paper P.

[0081] In the marking jetting operation performed by the ink-jet printer
according to this embodiment, the control unit 6 controls the head driver
54 so that the marking ink is jetted from the marking ink-jetting nozzles
340 toward the edge portion Pa of the recording paper P. Accordingly, the
marking ink, which is landed on the edge portion Pa of the recording
paper P, is more permeated in the thickness direction of the edge portion
Pa of the recording paper P, as compared with a case in which the ink
jetted from the nozzle 40 is landed on the recording paper P in the
ordinary jetting operation. Accordingly, the liquid droplets of the
marking ink, which are jetted onto the recording paper P in the marking
jetting operation, can be more permeated in the thickness direction of
the recording paper P, as compared with the droplets of the ink which are
jetted onto the recording paper P in the ordinary jetting operation. In
other words, it is possible to form the marking Pd which car be easily
conformed from the side of the recording paper P. Further, it is possible
to suppress the amount of consumption of the ink for the ordinary letting
operation, as compared with a case in which the same ink is used for both
of the ordinary jetting operation and the marking jetting operation.

Fourth Embodiment

[0082] Next, a fourth embodiment of the present invention will be
explained. FIG. 12 shows a schematic arrangement of an ink-jet printer
according to the fourth embodiment of the present invention. As shown in
FIG. 12, an ink-jet head 403 of this embodiment is a line type ink-jet
head. The ink-jet head 403 has a plurality of unillustrated nozzles which
are arranged in the scanning direction (left-right direction as shown in
FIG. 12) on the lower surface thereof to range over the entire region in
the scanning direction of the printing paper. Further, the ink-jet head
403 is constructed such that the ink droplets are jetted from the
plurality of nozzles onto the recording paper P in a state of being
positioned and fixed to the frame 4 at a predetermined liquid
droplet-jetting position. The plurality of nozzles are aligned in the
scanning direction to form four nozzle arrays. The four nozzle arrays are
arranged, side by side, in the paper feeding direction (upward-downward
direction in FIG. 12). The four color inks of black, yellow, cyan, and
magenta are jetted from the nozzles belonging to the four nozzle arrays
respectively.

[0083] In the marking jetting operation performed by the ink-jet printer
401 according to this embodiment, the ink droplets are jetted from the
nozzles facing the edge portion Pa of the recording paper P transported
by the transport rollers 5, and the marking Pd is formed at the side end
portion Pc of the recording paper P. In other words, the nozzles, which
are opposed to the edge portion Pa of the recording paper P transported
by the transport rollers 5, are exclusively used for the marking jetting
operation.

Fifth Embodiment

[0084] Next, a fifth embodiment of the present invention will be
explained. FIG. 13 shows a schematic sectional view illustrating an
ink-jet printer according to the fifth embodiment of the present
invention. FIG. 14A to 14D illustrate transport states of the recording
paper in the ink-jet printer according to the fifth embodiment of the
present invention, wherein FIG. 14A shows a situation in which the
recording paper is fed, FIG. 14B shows a situation in which the printing
operation is performed on one surface of the fed recording paper, FIG.
14C shows a situation in which the recording paper having been subjected
to the printing operation on one surface is inverted, and FIG. 14D shows
a situation in which the printing operation is performed on the other
surface of the inverted recording paper. FIG. 15 shows a schematic plan
view illustrating the printing operation on the recording paper by the
ink-jet printer according to the fifth embodiment of the present
invention.

[0085] As shown in FIG. 13, in the ink-jet printer 501 of this embodiment,
an inverting mechanism 510 is added to the ink-jet printer 1 of the first
embodiment, and the printing operation can be performed on the both
surfaces of she recording paper P.

[0086] In the ink-jet printer 501, the recording paper P, which is fed
from a paper supply port 511 (see FIG. 14A), is transported no an area
opposed no an ink-jet head 503 by the aid of two pairs of rollers 512 and
a guide member 518 (see FIG. 14F). In the ink-jet printer 501, the
recording paper P, of one surface facing the ink-jet head 503, is fed to
the inverting mechanism 510 by reversely rotating two pairs of rollers
515 shown in FIG. 13 (see FIG. 14C). After that, in the ink-jet printer
501, the recording paper P is inverted by guide members 516, 517 and two
pairs of rollers 519 which constitute the inverting mechanism 510. The
recording paper P is fed to the area opposed to the ink-jet head 503, and
the other surface of the recording paper P is opposed to the ink-jet head
503 (see FIG. 14D). The respective two pairs of rollers 512, 515, 519 are
driven and rotated by controlling an unillustrated motor by the control
unit 6

[0087] As shown in FIG. 15, when one surface of the recording paper P is
opposed to the ink-jet head 503 (when the recording paper P and the
ink-jet head 503 are opposed to one another for the first time in
relation to one sheet of the recording paper P), the control unit 6 of
the ink-jet printer 501 according to this embodiment controls the head
driver 54 so that the ink droplets are jetted from the nozzles 40 to
perform the ordinary jetting operation. When the other surface of the
recording paper P is opposed to the ink-jet head 503 by the aid of the
inverting mechanism 510 (when the recording paper P and the ink-jet head
503 are opposed to one another for the second time in relation to one
sheet of the recording paper P), the control unit 6 controls the head
driver 54 so that the ink liquid droplets are jetted from the nozzles 40
to perform the ordinary jetting operation and the marking jetting
operation.

[0088] The ink (marking Pd), which is jetted onto the edge portion Pa of
the recording paper P in the marking jetting operation, is more permeated
in the thickness direction of the recording paper P as compared with the
ink which is jetted onto the printing area Pb of the recording paper P in
the ordinary jetting operation. Therefore, if the marking jetting
operation is performed on one surface in addition to the ordinary jetting
operation on the one surface (i.e., the first time ordinary jetting
operation), and the recording paper P is inverted by the inverting
mechanism 510, then the ink, which is permeated into the edge portion Pa
of the recording paper P, is blurred.

[0089] Accordingly, when the marking jetting operation is performed
together with the ordinary jetting operation on the other surface (i.e.,
the second time ordinary jetting operation), the ink, which is permeated
into the edge portion Pa of the recording paper P, can be prevented from
any blur, because the recording paper P is immediately discharged after
the printing operation. It is also possible that the ordinary jetting
operation is performed on only one surface of the recording paper P, and
that the marking jetting operation is performed on the other surface. In
this case, the marking Pd can be confirmed from the side end portion Pc
of the recording paper P, while the marking Pd can be made inconspicuous
from one surface on which the ordinary jetting operation is performed, by
performing the marking jetting operation on the other surface.

Sixth Embodiment

[0090] Next, a sixth embodiment of the present invention will be
explained. FIG. 16 shows a schematic cross-sectional view illustrating an
ink-jet printer according to the sixth embodiment of the present
invention. In the ink-let printer 601 of this embodiment, the line type
ink-jet heads 403 of the fourth embodiment are provided so that they are
opposed to the both surfaces of the recording paper P respectively. The
printing operation can be performed on the both surfaces of the recording
paper P.

[0091] The ink-jet printer 601 has the two line type ink-jet heads 403a,
403b which are opposed to the both surfaces of the recording paper P
transported by two pairs of rollers 615 respectively. The two line type
ink-jet heads 403a, 403b are constructed in the same manner as the
ink-jet head 403 of the fourth embodiment. The nozzles, which are opposed
to one surface of the recording paper P, are formed on the lower surface
of the ink-jet head 403a. The nozzles, which are opposed to the other
surface of the recording paper P, are formed on the upper surface of the
ink-jet head 403b. The two ink-jet heads 403a, 403b are arranged at
positions deviated from each other in the paper feeding direction.

[0092] The control unit 6 of the ink-jet printer 601 according to this
embodiment is capable of controlling the head driver 54 so that the ink
liquid droplets are jetted from the ink-jet heads 403a, 403b to perform
the printing on the both surfaces of the recording paper P.

[0093] When the ordinary jetting operation is performed on only one
surface of the recording paper P in the ink-jet printer 601, the marking
letting operation is performed on the other surface of the recording
paper P. Specifically, the control unit 6 controls the head driver 54 so
that the ink liquid droplets are jetted from the ink-jet head 403a to
perform the ordinary jetting operation on the printing area Pb of one
surface of the recording paper P opposed to the ink-jet head 403a, and
the ink liquid droplets are jetted from the ink-jet head 403b to perform
the marking jetting operation on the edge portion Pa of the other surface
of the recording paper P opposed to the ink-jet head 403b.

[0094] Accordingly, the marking Pd can be confirmed from the side end
portion Pc of the recording paper P, while the marking Pd can be made
inconspicuous from one surface of the recording paper P on which the
ordinary jetting operation is performed. In this embodiment, the ordinary
jetting operation is performed on one surface of the recording paper P
opposed to the ink-jet head 403a, and the marking jetting operation is
performed on the other surface of the recording paper P opposed to the
ink-jet head 403b. However, the marking jetting operation may be
performed on one surface of the recording paper P opposed to the ink-jet
head 403a, and the ordinary jetting operation may be performed on the
other surface of the recording paper P opposed to the ink-jet head 403b.

[0095] Next, an explanation will be made about modified embodiments in
which various modifications are applied to the first to sixth embodiments
described above. In the embodiments described above, the marking is
formed at the side end portion disposed in the paper feeding direction of
the recording paper P. However, the marking may be formed at the side end
portion disposed in the scanning direction (at the side end portion or
portions disposed at the both ends in the paper feeding direction).

[0096] The marking may be formed not only at one side end portion disposed
in the paper feeding direction of the recording paper P, but the marking
or markings may be also formed at the other side end portion or the both
side end portions, by controlling the head driver 54 by the control unit
6 to execute the marking jetting operation.

[0097] Further, the two ink-jet heads may be provided for the ordinary
jetting operation and for the marking jetting operation, and the ordinary
jetting operation and the marking jetting operation may be performed by
controlling the respective ink-jet heads by the control unit. The larger
amount of the ink is permeated in the thickness direction of the
recording paper P in the marking Pd formed at the edge portion Pa of the
recording paper P as described above, as compared with the portion onto
which the inks are jetted in the printing area Pb. Therefore, it is
considerably feared that the ink may be adhered to the paper discharge
roller (for example, the transport rollers 5 and the pairs of rollers
615) arranged on the downstream side in the paper discharge direction as
compared with the ink-jet head. Accordingly, the paper discharge roller
is formed of a highly liquid-repellent material in the ink-jet printer
according to any one of the embodiments and the modified embodiments
described above, and thus it is possible to avoid the adhesion of the ink
to the paper discharge roller. For example, a portion of the paper
discharge roller, which makes contact with the recording paper, may be
coated, for example, with a fluorine-based resin. Alternatively, when the
area of the recording paper P, in which the marking Pd is formed, can be
previously specified for the sheets of the recording paper P having
various sizes, an area of the paper discharge roller, which is overlapped
with the marking Pd, may be previously cut out. Also in this case, it is
possible to avoid the adhesion of the ink to the paper discharge roller.